Uber background checks failed to detect the criminal record of a driver accused in the sexual assault of a female passenger last year, according to a lawsuit that charges the ride-hailing company with neglecting the safety of its female customers.

The lawsuit, which was originally filed in October by two unidentified plaintiffs, accuses Uber of conducting inadequate background checks on its drivers. Amendments to the suit filed Wednesday added that a driver accused of assaulting a female passenger in South Carolina last August had previously been arrested on suspicion of domestic abuse and was convicted of assault in connection with the arrest.

The lawsuit notes that the driver's conviction occurred in 2003 but that he did not apply to drive for Uber until 2015, some 12 years after his conviction. Uber's background check failed to catch the conviction because it only searches back seven years, according to the complaint.

Uber, which makes a smartphone app that connects people who want a ride with de facto cab drivers, has come under fire for dozens of sexual assaults allegedly carried out by its drivers worldwide. A handful of states, including California and Texas, havelaunched investigations into Uber, claiming it routinely fails to adequately screen drivers and has hired drivers with criminal histories.

"Uber continues to play fast and loose with laws and regulations that are set in place to ensure safety," Jeanne M. Christiansen, attorney for the plaintiffs, said in a statement. "It's precisely this corporate strategy that has directly resulted in our clients and many other women being put squarely in danger from individuals whose backgrounds we know were not fully vetted."

Uber responded by saying it was focused on the safety of its passengers.

"Safety is very important to us, and this driver was immediately and permanently barred from the platform," an Uber spokesman told CNET. "We continue to work with all parties as the process unfolds."

Uber has previously said it puts all potential US drivers through commercial background checks, running candidates' names through seven years of county and federal courthouse records, a multi-state criminal database, national sex offender registry, Social Security trace and motor vehicle records. Uber said it rejects anyone with a history of violent crimes, sexual offenses, gun-related violations or resisting arrest.

The lawsuit amended Wednesday involves two alleged cases of sexual assault in two different cities by two different drivers.

Jane Doe 1's alleged assault took place in Boston at around 2:30 a.m. local time on February 8, 2015, after she and her friends had been at a party, the complaint says. The Uber driver dropped off Jane Doe 1's friends first, drove her along an off-route detour and then groped her and forcibly kissed her, according to the complaint, which adds that she managed to unlock the car door and escape.

The complaint says Jane Doe 2 was at a bar with friends in Charleston, South Carolina, on August 9, 2015, when the group was picked up by an Uber driver. After dropping off her friends, the driver drove Doe 2 to a remote parking lot and raped her, according to the complaint. Doe 2 then escaped and got help, the document says.

In addition to seeking unspecified damages, the suit is requesting a jury trial and a permanent injunction against Uber to overhaul its safety measures. Plaintiffs are also asking the court to order Uber to boost its safety standards by adding several new measures. These new measures include 24-hour customer support hotlines in all cities in which it operates, requiring all drivers to install GPS tracking systems on their cars that would set off an alarm if deactivated, disabling child-lock features on passenger doors and conducting fingerprint-based background checks and in-person interviews with drivers.